Purification system

Abstract

A purification system includes a clutch that switches between transmitting and interrupting power of an engine to a driven device, which is driven by power of the engine and a motor, a catalyst that i) adsorbs nitrogen oxides if an air-fuel ratio is a threshold value or more, and ii) facilitates a reaction between unburned fuel and the adsorbed nitrogen oxides if the air-fuel ratio is less than the threshold value, a clutch controller that brings the clutch into the disengaged state thereby enabling the driven device to be driven solely by the power of the motor, and an operation controller that brings the air-fuel ratio of the engine to be less than the threshold value if the driven device is driven solely by the power of the motor.

1 . A purification system comprising:
 a clutch that switches between transmitting and interrupting power of an engine to a driven device, which is driven by the power of the engine and power of a motor;   a catalyst that i) adsorbs nitrogen oxides in exhaust gas of the engine if an air-fuel ratio is a predetermined air-fuel ratio or more, and ii) facilitates a reaction between unburned fuel contained in gas discharged from the engine and the adsorbed nitrogen oxides if the air-fuel ratio is less than the predetermined air-fuel ratio;   an acquisition part that acquires an adsorption amount of the nitrogen oxides adsorbed to the catalyst;   a clutch controller that controls the clutch to interrupts the power of the engine to the driven device if the driven device is driven by the power of the engine and the adsorption amount reaches or exceeds a predetermined value; and   an operation controller that brings the air-fuel ratio of the engine in operation to be less than the predetermined air-fuel ratio if the adsorption amount reaches or exceeds the predetermined value and the driven device is driven solely by the power of the motor.   
     
     
         2 . The purification system according to  claim 1 , wherein
 the motor is provided between the driven device and the clutch, and   the clutch is provided between the engine and the motor.   
     
     
         3 . The purification system according to  claim 1 , comprising:
 a generator that generates electricity using an output of the engine, wherein   the motor is driven by electricity of the generator.   
     
     
         4 . The purification system according to  claim 1 , wherein
 the acquisition part acquires a driving load of the driven device, and   when the adsorption amount reaches or exceeds the predetermined value, the operation controller i) decreases output ratio of the engine relative to the driving load and ii) increases output ratio of the motor relative to the driving load, with the clutch in an engaged state where the power of the engine is transmitted to the driven device.   
     
     
         5 . The purification system according to  claim 4 , wherein
 if the output ratio of the motor relative to the driving load becomes 1, the clutch controller brings the clutch into a disengaged state where transmission of the power of the engine to the driven device is interrupted.   
     
     
         6 . The purification system according to  claim 5 , wherein
 the catalyst facilitates a reaction between the unburned fuel and the nitrogen oxides at or above its activation temperature, and   the operation controller brings the air-fuel ratio to less than the predetermined air-fuel ratio when exhaust gas temperature of the engine reaches or exceeds the activation temperature after the clutch enters the disengaged state.   
     
     
         7 . The purification system according to  claim 6 , wherein
 the operation controller increases the exhaust gas temperature until the exhaust gas temperature reaches or exceeds the activation temperature if the exhaust gas temperature is lower than the activation temperature after the clutch enters the disengaged state.   
     
     
         8 . The purification system according to  claim 5 , wherein
 the clutch controller brings the clutch into the engaged state if the adsorption amount reaches or exceeds a lower limit value smaller than the predetermined value after bringing the clutch into the disengaged state.   
     
     
         9 . The purification system according to  claim 8 , wherein
 the operation controller decreases the output ratio of the motor relative to the driving load after the clutch enters the engaged state.   
     
     
         10 . The purification system according to  claim 1 , wherein
 the acquisition part acquires a greater value of the adsorption amount as an amount of exhaust gas discharged from the engine increases.   
     
     
         11 . The purification system according to  claim 1 , wherein
 the acquisition part references a data table indicating a relationship between an integrated value of an amount of exhaust gas and an adsorption amount to acquire an adsorption amount corresponding to an integrated value obtained by integrating an amount of exhaust gas discharged from the engine per unit time from a time point when the adsorption amount reaches a lower limit value of an amount that can be adsorbed to the catalyst to a current time point.